Abstract
Orthogonal experiments were performed to study the flexural strength of an eco-friendly concrete containing fly ash (FA) and ground granulated blast-furnace slag (GGBFS). The effects of different test parameters, such as water-binder ratio (W/B), FA content, GGBFS content, sand ratio, gravel gradation, and curing time, on the flexural strength of the concrete were analyzed. The significance level of each influencing factor and the optimal mixing proportion of the concrete were determined by range analysis and hierarchy analysis. It was found that the W/B ratio had the greatest influence on the flexural strength of the concrete. The flexural strength of the concrete decreased gradually with the increase of W/B. The GGBFS content and the sand ratio had a greater influence in the early stage of concrete curing. The middle and later stages of concrete curing were mainly affected by gravel gradation and the FA content. A flexural strength prediction model of the concrete was developed based on a backpropagation neural network (BPNN) and a support vector machine (SVM) model. It was noticed that the BPNN and SVM models both had higher accuracy than the empirical equation, and the BPNN model was more accurate than the SVM model.
Highlights
Concrete is one of the most widely used building materials due to its good quality and low price [1]
Since only the relationship between compressive strength and flexural strength of concrete at 28 days of age is given in the specification, the predicted results of 28-day concrete flexural strength in machine learning methods are chosen for comparison, and the results showed that the backpropagation neural network (BPNN) model still has the highest accuracy
Orthogonal experiments were performed to study the flexural strength of an eco-friendly concrete containing Fly ash (FA) and ground granulated blast-furnace slag (GGBFS). e effects of water-binder ratio (W/B) ratio, FA content, GGBFS content, sand ratio, and gravel gradation on the flexural strength of the concrete were investigated by range analysis and hierarchy analysis
Summary
Concrete is one of the most widely used building materials due to its good quality and low price [1]. Erefore, it is of great significance to improve the flexural strength of concrete [2]. Supplementary cementitious materials, such as fly ash, ground granulated blast-furnace slag, and silica powder, are generally used to improve the performance of concrete, reduce the waste stock, and lower the construction cost [3]. Golewski [7] studied the compressive strength and fracture toughness of concrete with FA contents of 20% and 30%. It was reported that the compressive strength and fracture toughness of concrete were significantly improved when the FA replacement ratio was 20%. Golewski [8] found that the optimal FA content to improve the fracture toughness of concrete was 17% (by weight). Atis [9] reported that the flexural strength of 70% FA-replaced concrete after 7, 28, 90, and 365 days was reduced by 46.83%, 24.71%, 26.2%, and 35.16%, respectively, as compared to that of 50% FA-replaced concrete
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